The cyclotron production of selected radionuclides using medium energy protons

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The cyclotron production of selected radionuclides using medium energy protons

Van der Meulen, N. P. (Nicolas Philip)

2008-03

ENGLISH ABSTRACT: Radiochemical research involving ion exchange chromatography is of paramount
importance to the future of radionuclide production at the Radionuclide Production
Group (RPG) of iThemba LABS. It is required for the production of high-activity
yields of radionuclides to effectively remove impurities and for the safety of the
operators performing such productions. The radiochemical separations of some new
products from their target material, as well as experiments to determine whether
production is viable, are described.
67Ga is currently being produced at the RPG and makes use of zinc targets. With the
production of ultra-pure 67Ga, it was necessary to remove any Fe(III) impurities from
the final product, such that it may be possible to label peptides with this product. The
use of Amberchrom CG161M for this purpose was found to be satisfactory.
Interest was shown in 88Y by an overseas company for the manufacture of sources.
While a method involving extraction of the radionuclide and the ion exchange thereof
using Chelex 100 chelating resin had been published, problems with the production
persisted. Three methods, using ion exchange chromatography, were devised to
produce the radionuclide, with two of them being adopted for production purposes.
Thick-target nuclear data have also recently been accumulated in collaboration with
colleagues from ATOMKI, Debrecen, Hungary.
There is a large demand for 82Sr for the manufacture of 82Sr/82Rb generators for
medical use. A method was developed to manufacture this radionuclide with thicker
(32 g) target material, bombarded in the Vertical Beam Target Station (VBTS), and to
separate 82Sr from its target material with the use of Purolite S950 chelating resin.
68Ge/68Ga generators are becoming increasingly important in the world of
radiopharmaceuticals. A project to develop a local generator was funded by the
Innovation Fund and research was performed to produce 68Ge, such that the generator
could be manufactured. This involved bombarding thicker Ga targets in the VBTS
and performing the chemical separation using AG MP-1 anion exchange resin. The final product was loaded onto generators, although tests performed on different
materials to the ones being marketed are also reported in this work.
A project was initiated to study the cluster radioactive decay of 223Ac via 14C and 15N
emission. To produce 223Ac for these observations, a Th target was bombarded. The
227Pa was separated from the target material using AG MP-1 macroporous anion
exchange resin and used as a source, which decayed to 223Ac. The chemical
separation and the drying of the final product onto a source plate were completed
within approximately 70 minutes from the end of bombardment. The work was
performed in collaboration with JINR, Russia, and University of Milan and INFN,
Italy.
133Ba has a half-life of over 10 years and is an expensive radionuclide to produce. It
has been used in medical and biological studies and there still appears to be a demand
for it. A method was devised, utilizing AG50W-X4 cation exchange resin, to separate
133Ba from its CsCl target material.
Agricultural specialists in the past have shown an interest in 28Mg, to determine the
uptake of the element in fruit. It has long been regarded by some of the local
researchers as an interesting project to investigate. It has been determined that the
product can be produced in reasonable quantities using LiCl target material, with ten
targets being bombarded in series using a 200 MeV proton beam delivered by the
Separated Sector Cyclotron. A method, involving the use of Purolite S950 chelating
resin, was devised to separate 28Mg from its target material.